(1) Field of the Technology
The present technology relates to an image forming apparatus, and in particular relates to an image forming apparatus including a waste toner collecting container for collecting waste toner.
(2) Description of the Prior Art
In the conventional image forming apparatuses based on electrophotography such as facsimile machines, printers and the like, image forming is performed by electrifying a rotationally driven photoreceptor drum by a charger, illuminating the photoreceptor drum with light in accordance with image information to form an electrostatic latent image, and applying toner to this electrostatic latent image by a developing unit to form a toner image. In some configurations called an intermediate transfer system, this toner image is temporarily transferred to an intermediate transfer medium such as a transfer belt or the like, then the toner image is transferred from the intermediate transfer medium to a recording medium such as sheet material, paper or the like, to produce a printout of the image. In other configurations, the toner image on the photoreceptor drum is directly transferred to a recording medium to produce a printout of the image.
In the photoreceptor drum (toner image bearer) on which toner images are formed in the thus configured image forming apparatus, at the transfer stage all the developed image information (toner image) on the photoreceptor drum cannot be transferred to the paper or the intermediate transfer medium. The transfer efficiency is usually, and roughly, estimated to be 85 to 95%, though this depends on the transfer mechanism used.
If a next printing operation is started without the toner that has not transferred to the paper, and remains on the photoreceptor drum, being cleaned, degradation of the print quality in the next printing operation will occur. To deal with this problem, the photoreceptor drum, after the transfer stage, and the intermediate transfer belt that receives a toner image from the photoreceptor drum and transfers it to the paper, are cleaned by associated cleaning units, so as to remove the leftover toner from them (cleaning stage). The toner collected at the cleaning stage is stored as waste toner into a waste toner box (waste toner collecting container).
The conventional waste toner box is removably mounted to the main body. When the waste toner box becomes full of waste toner, the box is unmounted from the main body, and mounted again after the waste toner is disposed or the box is replaced by a new empty waste toner box.
As a method for detecting the full waste toner box, there has been a conventionally known method in which, the waste toner collecting container is adapted to be retained by an elastic member such as a spring or the like, the downward shift of the waste toner collecting container due to the weight of the waste toner therein is detected by a sensor (see patent document 1: Japanese Patent Application Laid-open 2005-173451).
However, the above method suffers the problem that waste toner, as it falls into the waste toner collecting container, scatters because a gap arises between the waste toner discharge port for discharging waste toner, provided on the main body side of the image forming apparatus, and the waste toner receiving port for leading waste toner into the receptacle when the waste toner collecting container has moved down.
There is also another problem that, especially in a compact image forming apparatus, it is impossible to secure the space for storing a large quantity of waste toner because the vacant space in the apparatus has been limited so as to achieve its miniaturization. To deal with this, as a conventional technology, a waste toner collecting container which is formed to be extensible and contractible so that the capacity of the waste toner receptacle can be changed, has been disclosed (see patent document 2: Japanese Patent Application Laid-open H10-39601).
However, the toner collecting container configuration of patent document 2 needs to have an inner receptacle for storing waste toner and an exterior receptacle that is formed in a telescopic manner of multiple parts for covering the inner receptacle. As a result, there are problems that the receptacle configuration is complicated and that the quantity of waste toner collected in the receptacle is indistinct.